This invention relates to web winding and more particularly to a continuous turret-type winder and to a method of winding a web in which a pressure roll is maintained in contact with a winding roll throughout the winding operation.
Turret-type winders have commonly been used with roll changers or accumulators by which each of a pair of core-supporting spindles carried on the ends of the turret arms are sequentially loaded with a core. The cut edge of a web is attached to the core by a suitable web transfer or enveloper apparatus. At a particular point in the build-up of the winding roll it is indexed through approximately 180.degree. while the winding continues, to deliver the winding roll to an unloading station and to deliver a fresh core on the recently unloaded spindle of the turret arms to the web transfer station.
The continuous winding, on a turret-type winder of certain kinds of web materials, particularly non-porous materials such as plastic film, requires particular considerations in producing a roll which is uniformly wound. One important consideration is that of preventing air from being entrapped between the individual layers or wraps, so that succeeding wraps do not produce side slipping or otherwise produce a poorly wound roll. Thus, it has become common practice to employ a roll changer having a pressure roll positioned against the winding roll to control the hardness of the winding package. The function of the pressure roll is to expel the air layer at the incoming web and prevent this air from being trapped between the successive layers, which would otherwise make the completed wound package too soft or unstable. However, in turret-type winders, a particular problem presents itself in that during and following indexing of the winding roll, the winding roll of necessity moves away from the pressure roll on the roll changer apparatus.
The turret winder disclosed in the U.S. Patent of Penrod, No. 3,478,975 issued Nov. 18, 1969 to the assignee of this invention, was a successful improvement, particularly designed for impervious or non-porous web material such as plastic film. An auxiliary rider roll was pivotally mounted to the rotating turret structure and more particularly, on an arm pivoted to an offset arm forming an integral part of the turret structure. The turret-supported pressure roll could be brought against the winding roll even while it was still in the transfer station. This auxiliary pressure roll would take over the function of the pressure roll on the roll changer throughout the indexing motion of the turret and thereafter until the winding roll reached its maximum diameter, thereby reducing loss of continuity when the winding roll was moved, by the turret, out of the transfer station and into the loading station. However, due to the fact that the turret-supported pressure roll was designed to be used in conjunction with the primary pressure roll on the roll changer, in order to accommodate these rolls simultaneously at the beginning of the transfer function, it was necessary to position the auxiliary roll at a side of the core which was generally opposite from the web lead-in side and from the pressure roll associated with the roll changer. Accordingly, the auxiliary rider roll contacted the winding roll at a position spaced somewhat arcuately from the tangent line which the oncoming web formed with the roll, and the effectiveness of the turret-supported rider roll in eliminating entrained air between the wraps was substantially reduced as compared to the effectiveness of the pressure roll on the roll changer, which contacted the web just prior to its forming a nip with the building roll. Thus, due to this somewhat decreased effectiveness, variations in package hardness sometimes occurred where the outermost wraps were formed under the influence of only the auxiliary riding roll.
The turret-winder apparatus as disclosed in the Penrod patent was conventional to the extent that the new core could be loaded onto the spindle at the unloading station after the previously wound roll had been removed. This newly wound core could then be indexed by the turret to the web transfer station while the web was being wound on the other spindle. Guide rolls were provided on arms set at an angle to the primary spindle arms which were designed to engage the web during transfer and guide it under the turret apparatus to the winding roll. The path of the web from the roll changer to the turret was such that the web remained outside the rotational path of the turret as the newly placed core was indexed to the web transfer station. Thus, after cutting and transferring by the conventional enveloping apparatus, the web engaged the newly placed core at the outside surface thereof or the surface most remote from the axis of the turret.
The method by which the turret winder of the general type shown in Penrod was operated required the cores to be loaded at the roll changing or unloading station and this generally impeded the automation of the loading and unloading of such turret winders. It has, however, in recent years, become desirable to automate both the loading of the cores into the winder and the unloading of completely wound rolls from the winder, and the necessity of having to accomplish each of these functions essentially at the same station resulted in a complication, and further resulted in the necessity of having present at that station two substantially different kinds of handling equipment. Generally it was not possible to load cores into the arms of the turret at the web transfer station due to the fact that the web was running off of the roll changer and onto the winding roll along a path outside of the rotational orbit of the arms, and thus stood in the way of bringing cores up from a magazine of cores or the like and onto the unloaded spindles at the web transfer station.
Thus, there exists a need for a winder for handling web materials of the kind described above in which a pressure roll maintains continuous contact with the winding roll throughout the complete winding and roll change sequence, and in which the web always contacts the pressure roll at or prior to the winding nip, preferably with a partial wrap of the web about the pressure roll, throughout the entire winding process.